substage of immediately preceded by developmental stage oogenesis stage S9 oogenesis stage S10 oogenesis stage S10A Oogenesis stage which begins when all the oocyte associated follicular epithelium is columnar and all of the nurse cell associated follicular epithelium is completely squamous and ends when centripetal follicle migration begins. During this stage, the migrating border cells reach the oocyte. The oocyte is about 50% egg chamber length. FBdv:00005271 FlyBase_development_CV Temporal ordering number - 10110.